A big Sunday night BBC detective drama for the new year, brought to you by the award-winning team behind 'Wallander'? A chance to beam straight into the nation’s collective living room after years slogging away just beyond the limelight? Rufus Sewell, an actor often cheerfully unemployed and regularly underwhelmed by the job offers that come his way, still wasn’t sure. He had some questions.

First of all, would Aurelio Zen, a policeman treading the mean streets of Rome, be a smoker? 'In the books Zen tries to give up,’ the actor says of the series of novels, by the late Irish author Michael Dibdin, upon which the three 90-minute dramas are based. 'And I don’t want to lose that detail – someone struggling with addiction. It’s fun,’ the 43 year-old adds with his customary roguish twinkle.

After his own roaring twenties and thirties, the Englishman – now teetotal and nicotine-free – knows a thing or two about addiction. 'Cigarettes still look good to me,’ he sighs. 'That’s why it’s lovely playing Zen – I can live vicariously through myself! They’re herbal fags – and I specified very early on that I wanted honey-rose. I did want him to smoke, very much.’

Sewell was also fine with having to spend three months filming in Rome. He describes himself as not really having a home – he rents a flat in Los Angeles, where he lives with his girlfriend, but his son, Billy, eight, from his second marriage (both were short-lived), lives in London, so he’s used to shuttling back and forth.

In any case, he’s no stranger to working abroad. At the time of our initial meeting, in August last year, he’d just finished the Hungarian shoot for Ken Follett’s The Pillars of the Earth, broadcast on Channel 4 in November, in which he played a stonemason called, brilliantly, Tom Builder.

Sewell didn’t want Zen to be just another television cop. 'He should be kind of different. Not cheesy. From the first moment the producer mentioned the role to me, I just said: “as long as it’s funny. And as long as he’s not one of those corridor-striding w---ers”.’

What the actor means is he didn’t want to play a forceful, argy-bargy copper with a brusque manner and stains on his suit lapels. 'There are certain kinds of patterns that writers slip into and television producers slip into. The assumptions that are made unnecessarily just because people are used to it. Troubled past, blah blah blah, unconventional methods, blah blah blah.

'For me, I just wanted him to be completely believable as a bloke. You know? Not a man. A bloke,’ he says, sitting on a wall outside a villa on the outskirts of Rome, squinting into his lunchtime pasta in the August sunshine. 'And what I like about him in the books – not that I’ve read all of them – but also in the scripts, is that he gets it wrong a lot… His relationships are off and on and often in the sh--. And I think he’s more fun when he’s slightly behind the game, as opposed to ahead of it.’

The detective is a Venetian based in Rome. This makes him a perennial outsider, as does his scrupulous honesty. Dibdin, a long-time resident of Italy, wrote with scholarly knowledge of, and love for, the country. But his Italy is riddled with corruption; there are always shadows in the sunshine. Zen is forever weaving his way through political intrigue, police sleaze and general societal murk.

Published in 1988, Dibdin’s first outing for Aurelio Zen – in which Zen investigates the kidnapping of a powerful industrialist – is being made into one of the Zen dramas by Left Bank Pictures, the producers responsible for English-language adaptations of Henning Mankell’s Kurt Wallander novels, starring Kenneth Branagh in the Bafta-winning lead.

How did Sewell go about creating the Roman version of a 'bloke’?

'I don’t worry about what that is, to tell you the truth. For me, I hope a certain Italian-ness just kind of seeps into me by osmosis. But the idea of trying to slip in Italian hand gestures would only really serve to make me look like an awkward English t--t.’

London-born Sewell insists, with no hint of a shadow on his darkly handsome features, that he has no thoughts about potentially becoming a household name in his mid-forties. All he cares about is being offered good roles. He admits to frustration at not being offered the parts he thinks he deserves, or could be good at. A comedy, say, or a decent drama that doesn’t pigeonhole him as the baddy – he’s done enough of those, in films such as 'A Knight’s Tale', 'The Legend of Zorro' and 'The Holiday'.

'I’m very, very happy with my recognition/lack of recognition in England in terms of my life. In terms of household name-age,’ he shrugs. 'The public’s memory is very short, luckily.’ He doubts that any success Zen has – and securing a prime-time slot on BBC One on the first Sunday of the new year is already something of a coup – will give him any leverage or clout. But what about the other recent television sleuth hit, Sherlock Holmes? That’s done wonders for the career of Benedict Cumberbatch.

'I think I have a kind of boost-proof career in that respect! And I’m happy with that. Do I expect things? No. If it was about proving a point, I’ve done that before,’ he says, mentioning his pleasure at his well-received, very funny turn as Petruchio in 'The Taming of the Shrew' in 2005’s 'Shakespeare Retold' television series, and also his acclaimed appearances in London’s West End and on Broadway in Tom Stoppard’s 'Rock’n’Roll'.

'And I don’t feel undervalued, I just feel underused slightly.’

How’s his diary for the rest of the year looking?

'Empty,’ says Sewell, merrily forking into his pasta.

We meet again in late November at the Bafta theatre in central London.Thanks to his role as The Englishman in the Johnny Depp/Angelina Jolie thriller 'The Tourist', Sewell’s diary in the intervening months hadn’t been quite as free as he’d hoped. Today he has flown in from LA – the third of three transatlantic trips he’s making in as many weeks. He’s here for a screening of the first Zen drama, 'Vendetta', and to take part, alongside his glamorous Zen co-star Caterina Murino (she was a Bond girl in Casino Royale) in a Q&A session for film and television industry professionals.

In 'Zen, Vendetta', we meet a cool, stylish copper who manages to remain thus even though he lives with his mother. His uniform is a dark, well-cut suit and sunglasses; breakfast is always a cappuccino and a cigarette. Zen is busy playing office footsie with a colleague’s glamorous secretary (Murino) while reinvestigating the murder of a government contractor. Meanwhile, a vengeful parolee is busy gunning down all those who had a hand in sending him to jail.

This opening drama is enormous fun. It’s shot in a lovely, honeyed light – Rome looks fantastic – and the tone is fast, skippy and, in places, pithy. Sewell’s Zen is moral, upright and diligent. But also, well, a bit of a dude.

In the bar beforehand, Sewell, a man with a flair for accents and no stranger to comic stagy flamboyance, works the room merrily. He sticks to the soft drinks.

'People ask me if I miss it,’ he says of alcohol. 'If I was unhappier not drinking, if I missed it that much, I’d drink! I’m completely teetotal; it’s the only way I can do it.’

Back in LA, he prefers to stay home with his girlfriend – as to her identity, he’s never been one for divulging details about his partners (he had a long relationship with actress Helen McCrory in the early Nineties, and dated Alice Eve, who appeared alongside him in 'Rock’n’Roll'). But he says that after relocating to LA to film a short-lived American television drama, 'The Eleventh Hour', 'the job faded but I kind of had connections then, privately’.

Together they live a quiet life in LA. 'I don’t really go out.’ He says he was never a huge fan of red carpet events, 'but I was always into free drinks and knocking around, which can make you vulnerable to that kind of thing’.

After graduating from London’s Central School of Speech and Drama, Sewell worked on the London stage, with his breakthrough television role coming in the BBC’s 1994 production of 'Middlemarch'. He also established a reputation as something of a roué. He’s chirpily self-deprecating and brightly alert to his own foibles: 'I’m a fussy beggar,’ he notes of his approach to scripts, which is one reason he doesn’t get as many jobs as he might.

'I don’t have any shame about the way I conducted my professional life,’ he says, reflecting on his twenties and thirties. 'I mean, personal life, Christ, everyone makes mistakes. There’s always gonna be regrets that you have professionally, but I’ve always tried to behave well. I mean, maybe I was… ’ He stops. 'I always found it hard to get out of bed, that was the problem! I'm better now. But I’ve always believed very, very strongly that the way you treat people is more important than anything, professionally or otherwise.’

Why did he give up drinking and smoking?

'Um, I was drinking and smoking from very, very, very young, and I tend to do things to excess. And I felt I was endangering my health – very much with smoking. My dad died, I think, from smoking. He died young – he was a big smoker, big drinker, then he popped’ – he snaps his fingers – 'just like that, and I always had a sense of that.

'And that can propel you to do it [smoke and drink] at a young age, just as much as it can stop you. Probably more than it stops you. And I found myself in a position where I was getting in my own way.’

Were his habits compromising his professional capabilities?

'It was compromising everything,’ he says quietly. 'Everything.’

Sewell’s father, Bill Sewell, was an Australian animator who came to Britain, and he always told people to follow the trail of his hero, the poet Dylan Thomas. He had a studio in Soho and worked on the Beatles’ 'Yellow Submarine'.

Both Rufus and his son Billy have inherited Bill’s flair for art. Bill split from Rufus’s mother Jo when he was five, and died when Rufus was 10. In his teens Rufus ran a little wild – he was a boozy lad with orange hair who drummed in school punk bands with names like Tum Te Tum, Another Green World and Realistic Kamra – but today says that his 'Eighties t--t’ behaviour was nothing out of the ordinary for the era.

'The eyeliner wasn’t that unusual!’ he grins. 'For anyone who was at school with me circa 1984, it was pretty standard.’ With his smoking jacket, ever-present packet of Sobranie Cocktail cigarettes and love of David Bowie, 'I was the bloke who hung around the punks who wasn’t a punk.’

When we’d met in Italy he’d described himself as being brought up as a 'survivor’ – was he referring to his early familial trauma and tragedy?

He furrows his brow and thinks. 'There’s a danger to saying stuff like this – trying to paint yourself as some struggling waif. But we were relatively poor. An interesting mix of being well-spoken but poor. Or, rather, poor but with a piano! And an ostensibly posh name. But the fact is, I was on free school dinners, we ended up in council-assisted accommodation, my mum was on benefits. But my mum’s well-spoken, and me and my brother speak the same way – well-spoken London.

'And she brought us up on her own. My dad was useless with money so before he died, definitely she was really fending for herself. She had a vegetable round and we would live on what was left. And we were on hand-me-down clothes. House was falling apart. And we were pretty well looked after.’ He’s inherited his mother’s abilities to make do and mend.

'As a cook, for example, I always flourish with fewer, cheaper ingredients.’ In his student days: 'I was famous for Sewell’s Gruel! A tin of beans, a stock cube, blah blah, and I could make food for eight people!’ he says proudly.

He says he applied similar methodology at drama school. If he didn’t get the part he wanted and was instead confined to playing 'the butler’ or 'the old man’, he wouldn’t sulk. 'You’re not gonna prove to anyone that you should be cast in better parts if the butler looks p---ed off.

'So for me at drama school, it was making the most of an opportunity, being a bit of a scavenger. And it was kind of the way I saw my mum – really managing brilliantly and knowing how to not make any waste.’

Sewell says he has Billy 'every couple of weeks. It just takes a little bit of arranging. Most of my finances and energy goes into keeping all that working.’ Does he fly economy? 'Absolutely!’ he says with no hint of shame.

'If I start getting into needing a certain class of travel I just can’t afford to keep doing it.

'I’ve discovered that I’ve never had much respect for money, and that has meant that money has ended up ruling me a little bit more than it should have. So I’m trying to learn – at this late stage in life! – to actually control that.

'It’s a matter of just living relatively simply. I don’t want to find myself cornered and being offered something second-rate and wanting to do it for the wrong reasons. I’ve never done that before.’